Means for tightening current supply plates on electrodes in electric furnaces



Nov. 2 1, 1967 E. ARCHINAL ET AL 3,354,255 I MEANS FOR TIGHTENINGCURRENT SUPPLY PLATES ON ELECTRODES IN ELECTRIC FURNACES 2 Sheets-Sheet1 Filed June 29, 1964 Nov. 21, 1967 E. ARCHINAL ET AL MEANS FORTIGHTENING CURRENT SUPPLY PLATES ON ELECTRODES IN ELECTRIC FURNACESFiled June 29, 1964 2 Sheets-Sheet 2 m f r I l y L. I i i 1% My 2 If, w.I F v. I I E W 1% l l b y v N (N I u *2; I I g I i I I \5 I Q I [L I I IUnited States Patent F 3,354,255 MEANS FOR TIGHTENING CURRENT SUPTLYPLATES ON ELECTRODES IN ELECTRIC FUR- NACES Ernst Archinal, Hermulheim,near Cologne, and Georg Wehlitz, Efieren, near Cologne, Germany,assiguors to Knapsack-Griesheim Aktiengesellschaft, Knapsack, nearCologne, Germany, a corporation of Germany Filed June 29, 1964, Ser. No.378,535 Claims priority, application Germany, June 29, 1963, K 50,097 11Claims. (Cl. 13-16) The present invention relates to means forelastically tightening current supply plates on electrodes in electricfurnaces.

The supply of current to the electrodes of electric furnaces has alwaysbeen associated with certain difficulties. Usually, power is suppliedthereto through current supply plates contacting the electrode in radialrelationship. Depending on operational requirements, the current supplyplates are either held in close contact with the electrode or electrodeshell, or in loose contact therewith under low contact pressure, so asto permit e.g. necessary interval advancement of the electrode tocompensate for electrode consumption, or out of contact therewith.Whatever the specific means used for tightening the current supplyplates to the electrode or for loosening them, they are always requiredto include structures receiving the reaction pressure of the meansapplying the contact pressure to the current supply plates. Cotters,screw mechanisms, hydraulic or pneumatic pressure may be used as thecontact pressure applying means and, e.g. a rope collar or generally acast collar having a box-like cross-sectional area is used as the meansreceiving the reaction pressure.

The present invention is based on the observation that considerably morefavorable operational conditions can be created for smaller expense byproviding a thrust collar comprising at least two groups of a pluralityof pipes hinged so as to form a collar extending from hinge to hinge andencircling the electrode so as to be radially spaced therefrom, and byproviding a stationary casing receiving the actual pressure-applyingmeans in the group of pipes locally allotted to each current supplyplate.

In one embodiment of the present invention, each group of pipes startswith an ends in a hinge joint portion. The hinge portions and thecasings have bores for the passage of cooling water, and each group ofpipes together with the hinge joint portions and casings fastenedthereto forms a separate cooling water circuit.

Each casing is provided with a thrust bolt having an electricallyinsulated front end portion. The thrust bolt is extended in rectangularrelationship with respect to the electrode axis and extended through abore disposed in the otherwise closed casing in the casing portionfacing the electrode. The thrust bolt is movable along its longitudinalaxis and shiftable through springs, which rest on a shoulder of thethrust bolt, by turning a threaded bush inserted in an internal threadcarved out in the anti-electrode casing portion.

The pipes in parallel relationship, vertically superposed with respectto the electrode axis so as to form a pipe grouping having link membersrigidly connecting them disposed therebetween.

The thrust collar is supported by the current supply plates.

In a second embodiment of the present invention, each group of pipesprovided with hinge parts at the respective front end and tail endportions thereof comprises two identical, vertically superposed pipesspaced from one another with the casings receiving the actualpressure-applying means being welded therebetween in pipe cut-outsfacing each other.

3,354,255 Patented Nov. 21, 1967 In this second embodiment of thepresent invention, the casing is a unilaterally closed hollow cylinderhaving a central bore disposed in its bottom portion and an internalthread carved into the opposite open end portion of the cylinder whichhas recessed grooves disposed at two positions in the cylinder shellwhich are opposite to one another and is welded between the pipe cut-outprovided in the pipes supporting the cylinder.

In the second embodiment, each casing is provided with a shoulderedmovable thrust bolt arranged in rectangular relationship with respect tothe electrode axis, extended through a central packed bore in the bottomportion of the casing and movable along its longitudinal axis.Interposed springs and a screw cap screwed into the internal thread ofthe casing maintain the thrust collar in position, the front end portionof the springs resting on the shoulder of the thrust bolt and the tailend portion thereof resting on an exchangeable spacer ring immovablyfastened to the thrust bolt.

The thrust bolt used in this second variant is electrically insulatedand suspended from the supporting ring allotted to the current supplyplates.

In both variants, the thrust collars are made of antimagnetic materialso as to minimize electric losses.

The invention is shown diagrammatically in the accompanying drawings inwhich:

FIG. 1 is a cross-sectional view of an electrode and a top plan view ofa thrust collar encircling the electrode;

FIG. 2 is a longitudinal section of a hinge part and FIG. 3 is alongitudinal section of the allotted counterpart;

FIG. 4 is a longitudinal section of a casing with the allotted pressureapplying means;

FIG. 5 is a longitudinal section taken along line VV of the electrode,the allotted current supply plate and the allotted thrust collar;

FIG. 6 is a longitudinal section taken along line VIVI of the. casing ofthe second embodiment with the allotted pressure-applying means, and

FIG. 7 is a side view of the casing with portions of an allotted groupof pipes.

In FIG. 1, electrode 1 is in close contact with the current supplyplates arranged uniformly around the electrode in encirclingrelationship. One of the current supply plates is shown in the drawingand identified by reference numeral 2. To each current supply plate 2there belongs an adjustable means applying contact pressure in radialrelationship with respect to the electrode, the individualpressure-applying means being interconnected by pipes 21 so as to form acollar, i.e. the thrust collar encircling electrode 1.

As shown in the embodiment represented in FIGS. 1 to 5, eachpressure-applying means comprises a casing 3 having a thrust bolt 4inserted therein which is extended towards electrode 1 and movable alongits axis directed towards the electrode axis and forced into contactwith current supply plates 2 by adjustable springs applying pressure inradial relationship with respect to the electrode.

The end portion of thrust bolt 4 facing electrode 1 is provided with aspecial terminal structure 5 which is electrically insulated from thrustbolt 4 by intermediate electrically insulating layers 6 because inoperation structure 5 is in contact with the electrically charge currentsupply plate 2.

Casings 3 have through bores 10 disposed in the horiozntal plane whichopen into the lumen of pipes 21 so that a cooling medium can be causedto flow therethrough.

A recessed bore in casing 3 (FIG. 4) is provided with a carved nutthread 9 receiving screw socket 8 which in turn receives the axiallyshiftable thrust bolt 4 having a shoulder 45 and a sealing packing 30disposed at its may be designed as shown in FIGS.

front end portion, and also receives a pressure spring, e.g. a helicalspring. By turning screw socket 8, thrust bolt 4 can be axiallydisplaced, and the contact pressure applied to the current supply plate2 can be regulated, the thrust collar receiving the reaction pressure.

The thrust collar is composed of several parts, e.g. in FIG. 1 of twosubstantially similar halves lying in the same horizontal plane, whichare hinged. Each hinge comprises two main parts, i.e. the inner hingepart 11 of FIG. 2 and the outer hinge part 16 of FIG. 3, which arefitted into one another in conventional manner and flexibly anddetachably connected with one another by a hinge bolt (not shown in thedrawing).

The inner hinge part 11 has passageways 14 and 15 for the passage ofcooling water. The joints to the annular passageway 15 are outside thesectional plane and therefore are not shown in the drawing. The hingebolt is extended through bore 12 of bush 13.

The outer hinge part 16 has passageways l9 and 2t) for the passage ofcooling water, the joints to annular passageways which again are outsidethe sectional plane being not shown in the drawing. The hinge bolt whichis preferably of conical shape is extended through bores 17 of bushes18.

As shown in FIG. 1, each of hinge parts 11 or 15 is rigidly connected toa casing 3, e.g. tight-welded thereto. Care should be taken that thebores 10 disposed in casings 3 for the passage of cooling water coincidewith the alloted bores 14 or 19 in hinge parts 11 and N. If a two-partthrust collar is used, each of the two halves thereof will thuscommunicate with a separate cooling water circuit extended from hingepart to hinge part, the cooling water inlet socket being defined in FIG.1 by reference numeral 27 and the cooling water outlet socket beingdefined by the reference numeral 28.

FIG. 5 indicates how the thrust collar of this invention is held inaltitude position with respect to the current supply plates.Draw-in-bolts 22 and 24, which are hinged through flexible joint 23,serve to suspend the current supply plateshown on a reduced scale fromcantilever 29 fastened to protecting pipe which in turn is fixed to thestationary structural part 26, e.g. the furnace housing. At its lowerend, the current supply plate is provided with a cantilever 43 whichserves as a support receiving casing 3, if necessary through aninterposed shim plate 44 permitting adjustment of the altitude positionof the casing.

If a two-part thrust collar is concerned, it is assembled by firstplacing the two halves thereof on cantilevers 43, then fitting hingeparts 11 and 16 into one another and ultimately inserting the hingebolts into bores 12 and 17. After adjustment of the altitude position ofthe thrust collar with the aid of shim plate 44, thrust bolts 4 areadvanced by turning thread bushes 3 until the desired contact pressureis produced. The thrust collar is loosened and removed in a reverseorder of succession.

In the second embodiment of this invention, which is illustrated inFIGS. 6 and 7 and preferably used in furnaces with low base supportedelectrodes, the electrode is again surrounded by pipe groupings 39 andwhich open with an end in hinge parts (not shown in the drawing)connecting the pipes so as to form an endless collar. As shown in FIGS.6 and 7, each pipe grouping comprises two identical pipes 39'and 40arranged vertically one above the other and spaced from one another.Each pipe grouping starts with and ends in a hinge part which 2 and 3.At least two such pipe grouping 39 and 40 are required so as to form aclosed circle, the inner and outer hinge parts being hinged together soas to form aring by means of a hinge bolt, which is preferably ofconical shape, and extended through bores 12 and 17 The pipe groupingsserve as the support receiving the casings with the pressure-applyingmeans. On places opposite to each other, the casings 31 are providedalong two surface lines with recessed grooves 32, and pipes 39 and 40have corresponding cutouts disposed on sides facing each other, so thatthe casings 31 can be inserted and welded to the pipes as shown in FIGS.6 and 7.

In operation, cooling water is caused to flow through pipes 39 and 4tand the allotted hinge parts in a circuit separate for each pipegrouping, and to flow around casing 31. The recessed grooves 32 areintended to obviate undesired throttling of the cooling water flow inpipes 39 and 4d and to ensure intense cooling of casing 31.

The thrust bolt 33 with the allotted shoulder 34 inserted in the bore ofcasing 31 slides in the bore of the casing and is guided in the casingportion 31 facing the electrode by means of the bore provided withpacking 38. The tail end smaller in diameter of thrust bolt 33 issurrounded by springs, preferably plate springs 35, which rest onshoulder 34 and are forced against shoulder 34 by means of spacer ring36 held in immovable position on thrust bolt 33, e.g. by means of Seegerring 41. Thesprings are thereby given a certain initial tension whichunder otherwise identical conditions depends on the thickness of spacerring 36 and thus can be predetermined as desired by using spacers ofvariable thickness.

After assembly, thrust bolts 33, springs 35, spacer 36 and Seeger ring41 will form a unit which is inserted as such in casing 31. Screw cover37 fully screwed in adjoins spacer 36 and ensures that return movementof the thrust bolt 33 into casing 31 requires out-weighing the force ofsprings 35. In other words the current supply plates are held in elasticcontact with the electrode.

Packing 38 seated in an annular groove disposed in the central bore ofcasing 31 prevents solids, vapors and gases included in the furnaceatmosphere from penetrating into the interior of casing 31.

In the second embodiment of the present invention comprising a thrustcollar especially for use in furnaces with low base supportedelectrodes, the thrust collar is disposed inside the low base electrodesupport having a cooling water jacket and suspended from the bearingring receiving the current supply plates. The upper side of pipe 39 hassuspension ledges 42 fastened thereto and operatively connected with acorresponding hanger attachment fixed to the bearing ring. Unless thebearing ring itself is electrically insulated, e.g. from the buildingstructure, the attached hangers have to be designed so as to includeelectrically insulating link members.

The thrust collars advantageously consist of antimagnetic steel in orderto keep electric losses low.

The two thrust collar types disclosed in the present invention offervarious advantages over the conventional means. Primarily, the weight isinferior to the weight of conventional cast thrust collars which usuallyhave a box-like cross-sectional area. Furthermore, each pipe groupingextending from hinge to hinge represents a single cooling water circuithaving a cross-sectional area remaining substantially constant. Coolingwater can therefore be caused to flow therethrough at a ratesufliciently high to ensure good heat transfer data and to keep insidepipe soiling low. Hinges l1 and 16 as well as casings 3 or 31 form partof the respective cooling water circuit and therefore need no furtherthermal insulation. Still further, it is no longer necessary to usespecial means in order to prevent the hinges and casings from becomingsoiled. Assembly and disassembly of the thrust collar are facilitated,and the space requirements are so small that charging devices can beemployed in open furnaces equipped with the present thrust collars whichin a special form of construction can also be used in closed furnaceshaving low base supported electrodes.

We claim:

1. An apparatus for elastically tightening current supply plates onelectrodes in electric furnaces consisting substantially of a cooled andhinged thrust collar allotted to each electrode concentricallyencircling the electrode and provided with adjustable means applyingcontact pressure to the current supply plates in radial relationshipwith respect to the electrode axis, which comprises a thrust collarcomprising at least two groups of a plurality of pipes complementary toeach other so as to form a circle encircling the electrode so as to beradially spaced therefrom; a plurality of hinges connecting theindividual pipes so as to form an endless hinged collar, a plurality ofcasings, each individual casing receiving means applying contactpressure to the current supply plates and rigidly disposed in theindividual groups of pipes locally allotted to each current supplyplate.

2. An apparatus as claimed in claim 1, which comprises several groups ofpipes, each pipe thereof starting with and ending in a hinge; aplurality of hinges connecting the pipes; a plurality of casingsreceiving the contact pressure applying means; bores disposed in thesaid hinges and the said casings for the pass-age of cooling water, eachgroup of pipes with the bores disposed in the allotted hinges and thecasing forming a separate cooling water cycle.

3. An apparatus as claimed in claim 1, which comprises a plurality ofcasings; a thrust bolt having an electrically insulated front portion; abore disposed in the otherwise closed casings in the casing portionfacing the electrode; a sealing packing sealing the said bore in thesaid casing portion, the said thrust 'bolt being disposed in eachindividual casing in rectangular relationship with respect to theelectrode axis and so as to be movable along its longitudinal axis inthe said casings and being extended through the said bore in the saidcasing portion; springs inserted in the said bore and resting with theirfront end portion on a shoulder of the said thrust bolt; a pivotablescrew socket disposed in the said casing permitting movement of the saidthrust bolt in the said casing; and an internal thread disposed in thecasing in the casing portion opposite to the electrode, the saidinternal thread receiving the said screw socket which is pivotabletherein.

4. An apparatus as claimed in claim 1 which comprises several groups ofsuperposed pipes arranged in parallel relationship with respect to oneanother, all pipes being embraced by the same hinges and the samecasings; and link members -inserted between the superposed pipes so asto rigidly interconnect the respective pipes.

5. An apparatus as claimed in claim 1, comprising two groups ofsuperposed pipes.

6. An apparatus as claimed in claim 1, wherein the current supply platessupport the thrust collar.

7. An apparatus as claimed in claim 6, comprising cantilevers attachedto the current supply plates receiving the thrust collar casings.

8. An apparatus as claimed in claim 1, comprising several groups ofpipes starting with and ending in hinges and consisting of two identicalvertically superposed pipes having cut-outs in pipe sections facing eachother and receiving the casings with the pressure applying means, thecasings being inserted in the said cut-outs and fastened to the saidpipes.

9. An apparatus as claimed in claim 8, wherein the casing comprises aunilaterally closed hollow cylinder, a central bore disposed in thecylinder bottom portion facing the electrode, an internal threaddisposed in the opposite open cylinder portion, grooved recessesdisposed at two cylinder positions opposite to each other, the cylinderbeing fastened between the cut-outs of the pipes supporting the saidcylinder.

10. An apparatus as claimed in claim 9, which comprises several casings,a thrust bolt having a shoulder, the said thrust bolt being extended inrectangular relationship With respect to the electrode axis and beingarranged so as to be movable along its longitudinal axis; a bore havinga sealing packing and disposed in the bottom portion of each casing; thethrust bolt being extended through the said bore; springs and a screwcover holding the said thrust bolt in position and screwed into theinternal thread of the casing; and an exchangeable spacer ring fastenedto the said thrust bolt so as to be immovable in one direction, thefront end portion of the springs resting on the shoulder of the saidhrust bolt and the tail end portion of the springs resting on the saidspacer ring.

11. An apparatus as claimed in claim 8, wherein the thrust collar issuspended from a bearing ring allotted to and supporting the currentsupply plates so as to be electrically insulated therefrom.

References Cited UNITED STATES PATENTS 2,135,408 11/1938 Moore 13-162,477,077 7/1949 Moore 1316 2,949,496 8/ 1960 Inglesrud et al. l3l6-2,632,780 3/1953 Whitehouse 13-16- BERNARD A. GILHEANY, PrimaryExaminer. H. B. GILSO-N, Assistant Examiner.

1. AN APPARATUS FOR ELASTICALLY TIGHTENING CURRENT SUPPLY PLATES ONELECTRODES IN ELECTRIC FURNACES CONSISTING SUBSTANTIALLY OF A COOLED ANDHINGED THRUST COLLAR ALLOTTED TO EACH ELECTRODE CONCENTRICALLYENCIRCLING THE ELECTRODE AND PROVIDED WITH ADJUSTABLE MEANS APPLYINGCONTACT PRESSURE TO THE CURRENT SUPPLY PLATES IN RADIAL RELATIONSHIPWITH RESPECT TO THE ELECTRODE AXIS, WHICH COMPRISES A THRUST COLLARCOMPRISING AT LEAST TWO GROUPS OF A PLURALITY OF PIPES COMPLEMENTARY TOEACH OTHER SO AS TO FORM A CIRCLE ENCIRCLING THE ELECTRODE SO AS TO BERADIALLY SPACED THEREFROM; A PLURALITY OF HINGES CONNECTING THEINDIVIDUAL PIPES SO AS TO FORM AN ENDLESS HINGED COLLAR, A PLURALITY OFCASINGS, EACH INDIVIDUAL CASING RECEIVING